Chronic back problems cause pain and disability for a large segment of the population. Frequently, the cause of back pain is traceable to diseased disc material between opposing vertebrae. When the disc material is diseased, the opposing vertebrae may be inadequately supported, resulting in persistent pain. Surgical techniques have been developed to remove all or part of the diseased disc material and fuse the joint between opposing vertebral bodies. Stabilization and/or arthrodesis of the intervertebral joint can reduce the pain associated with movement of a diseased intervertebral joint. Spinal fusion may be indicated to provide stabilization of the spinal column for a wide variety of spine disorders including, for example, structural deformity, traumatic instability, degenerative instability, post-resection iatrogenic instability, etc.
Generally, fusion techniques involve partial or complete removal of the diseased disc and packing the void area with a suitable matrix for facilitating a bony union between the opposing vertebral bodies.
Surgical devices for facilitating interbody fusion are known. Some devices are positioned external to the intervertebral joint during the fusion process. Other devices are positioned within the intervertebral joint. Devices positioned within the joint space typically distract the joint space and provide stabilization by causing tension on the annulus fibrosus and other supporting tissues surrounding the joint space. Examples of devices positioned within the joint space are disclosed in, for example, U.S. Pat. Nos. 5,458,638, 5,489,307, 5,055,104, 5,026,373, 5,015,247, 4,961,740, 4,743,256 and 4,501,269, the entire disclosures of which are incorporated herein by reference. Some systems use both external fixation and internal fixation devices.
Regardless of the type or location of the fusion device, a bone graft and/or other implant is often used to facilitate new bone growth. The surface area, configuration, orientation, surface texture and deformity characteristics of an implant or bone graft placed in the disc space can affect the stability of the joint during fusion and thus affect the overall success of a fusion procedure.
Accordingly, the present invention is directed to unique implants or bone grafts that can be inserted at a fusion site, with or without other stabilizing systems, and instruments and methods for inserting the same.